The International Contact Dermatitis Research Group proposes a classification for the clinical presentation of contact allergy. The classification is based primarily on the mode of clinical presentation. The categories are direct exposure/contact dermatitis, mimicking or exacerbation of preexisting eczema, multifactorial dermatitis including allergic contact dermatitis, by proxy, mimicking angioedema, airborne contact dermatitis, photo-induced contact dermatitis, systemic contact dermatitis, noneczematous contact dermatitis, contact urticaria, protein contact dermatitis, respiratory/mucosal symptoms, oral contact dermatitis, erythroderma/exfoliative dermatitis, minor forms of presentation, and extracutaneous manifestations.

The utility of the ear crease sign, anterior tragal crease (ATC), as a marker of atherosclerosis is yet to be established. The intima-media thickness of the common carotid artery (IMT-CCA) has been used as a noninvasive surrogate marker for atherosclerosis. History of traditional risk factors for atherosclerosis was obtained from 147 volunteers; ear examination was also performed and venous blood was drawn for laboratory analysis. The volunteers then underwent an ultrasonography measurement of the IMT-CCA. In univariate analysis, presence of ATC, age, underlying hypertension, diabetes mellitus, ischemic heart disease, cerebrovascular disease, cigarette smoking, low-density lipoprotein, and high-sensitivity C-reactive protein were significantly associated with the IMT-CCA. Further multivariate analysis confirmed a significant association between the presence of ATC and IMT-CCA, when adjusted for other factors (adjusted β = .010, 95% confidence interval: 0.0021-0.019). Anterior tragal crease is a potential clinical sign that can predict atherosclerosis. The sign is easily recognizable and may help health-care professionals to identify those at risk of atherosclerosis, especially in people with no clinical signs of the disease.

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Several authors have commented upon the skills of detection required in making a diagnosis of allergic contact dermatitis. Here, we emphasise the search for clues in a systematic manner. We describe four stages as part of a systematic method for diagnosing allergic contact dermatitis. Firstly, elimination (or inclusion) of non-allergic diagnoses. Secondly, perception: the pre-patch test diagnosis and the 'three scenarios' principle. Thirdly, detection: optimising the sensitivity of the patch test process. Fourthly, deduction: diagnosing allergic contact dermatitis by associating the dermatitis with the allergen exposure. We further compare and contrast the pre-patch test history and examination with the markedly different one ('microhistory' and 'microexamination') used after patch testing. The importance of knowledge of contact dermatitis literature is emphasised with a review of recent publications. Finally, we also highlight the use of contact allergy profiling as an investigative tool in the diagnosis of allergic contact dermatitis.

Linked Article: Kock et al. Br J Dermatol 2016; 174:1042–1050.

Adding topical silicone gel to ablative Er:YAG laser treatment may provide additional benefits in improving acne scars.

In the first conundrum, permanent hair dyeing involves the use of aromatic amines such as pphenylenediamine (PPD), whose oxidation is pivotal to the dyeing process, but also generates potent allergens. Despite prolonged efforts by industry to search for safer alternatives, hair dyeing is still reliant on this type of aromatic amine. In the second conundrum, patch testing with 1% PPD remains the most useful screen for hair dye contact allergy. However, there is a very small but real risk of actively sensitizing the patient. Lowering the PPD concentration below 1% significantly reduces test sensitivity and diagnostic utility. Here, we argue that by applying Friedmann's principles of contact sensitization each conundrum can be addressed from a new perspective. These principles indicate that, when the exposed area of skin is small (<1 cm 2 ), induction of contact allergy is sharply reduced, whereas elicitation of allergy is unaffected. Careful reflection on this principle suggests that we can predict where hair dye sensitization is most likely to occur, indicates a strategy to reduce the chance of contact sensitization occurring in consumers as a result of hair dyeing, and how we might mitigate the risk of active sensitization resulting from diagnostic patch testing.

Linked Article: Gubán et al. Br J Dermatol 2016; 174:533–541.